Ion implantation is used to perform a variety of functions. One such function is the doping of a semiconductor material, such as a wafer, to change its electrical properties. The goal of this process is to create a region within the substrate that has a polarity that may be different from the surrounding area. This process is used to develop integrated circuits, used in electronic components such as processors, memories, and other devices. In this embodiment, techniques such as, but not limited to, CVD, PECVD, plasma immersion and beamline implantation, may be used to introduce ions to the substrate.
More recently, interest has grown in using ion implantation to cleave a thin film of material from a bulk substrate. There are several methods of performing a cleave process, such as one referred to as “SmartCut”. This process is used for many applications, including the preparation of silicon-on-insulator (SOI). Briefly, a semiconductor substrate, such as a wafer, receives a surface treatment to oxide the surface. This creates an insulating layer around the substrate. An ion implantation of hydrogen and/or helium is then applied to the substrate. In some embodiments, the substrate is then flipped and bonded to a handle substrate. This handle substrate may be silicon, quartz or some other suitable material. The implanted hydrogen or helium ions tend to cause bubbles while the substrate is being annealed. These bubbles may aggregate to form a layer within the substrate. The depth of this layer is dependent on the concentration and energy of the hydrogen ions, as well as the anneal time. This layer weakens the substrate at that position, allowing it to be cleaved. This cleaved interface is then smoothed, using techniques such as chemical-mechanical polishing (CMP). The resulting film and handle substrate is then suitable for use in a SOI process. The remainder of the original semiconductor wafer can be reused to create another thin film.
In addition to the SOI process, cleaving processes are also gaining interest for other applications, such as a method of fabricating solar cells. As with SOI, these thin films are susceptible to strain, which can deform or destroy the film. Accordingly, it may be desirable to detect and monitor the delamination process. Furthermore, in addition to monitoring the delamination process, it would be beneficial to control the thin film delamination process. Additionally, it would be desirable if these techniques were used to determine delamination of other surfaces, such as chamber walls and equipment.